math_expressions 2.0.0

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A library for parsing and evaluating mathematical expressions, supporting real numbers, vectors, and basic interval arithmetic.

math_expressions #

A library for parsing and evaluating mathematical expressions.

  • Performs evaluations in real, vector, and interval contexts.
  • Supports expression simplification and differentiation.

math_expressions is inspired by mathExpr for Java and distributed under the MIT license.

Features #

  • Evaluation of expressions in various modes: Real, Vector and Interval.
  • Parsing, simplification and differentiation of mathematical expressions.
  • Supporting most basic math functions out of the box.
  • Extensible through custom function definitions in code.
  • Well documented and tested.

This package contains a very simple command-line interpreter for real numbers:

pub run math_expressions:interpreter

What's not working yet? #

  • Some evaluations in vector and interval space (especially functions).
  • N-dimensional vectors. Curently no more than four dimensions are supported.
  • The parser only works for real numbers.
  • Complex numbers.

Suggestions and pull requests are always welcome!

Usage #

Below are two basic examples of how to use this library. There also is some additional example code available.

1. Expression creation and evaluation #

This example shows how to evaluate

Equation 1

for xy

Build the expression

You can either create an mathematical expression programmatically or parse a string.

  • Create the expression programmatically:
  Variable x = Variable('x'), y = Variable('y');
  Power xSquare = Power(x, 2);
  Cos yCos = Cos(y);
  Number three = Number(3.0);
  Expression exp = (xSquare + yCos) / three;
  • Create the expression via the parser:
  Parser p = Parser();
  Expression exp = p.parse("(x^2 + cos(y)) / 3");

Evaluate the expression

  • Bind variables and evaluate the expression as real number:
  // Bind variables:
  ContextModel cm = ContextModel();
  cm.bindVariable(x, Number(2.0));
  cm.bindVariable(y, Number(Math.PI));

  // Evaluate expression:
  double eval = exp.evaluate(EvaluationType.REAL, cm);

  print(eval) // = 1.0

2. Expression simplification and differentiation #

This example shows how to simplify and differentiate

Example 2

  • Expressions can be simplified and differentiated with respect to a given variable:
  Expression exp = p.parse("x*1 - (-5)");

  print(exp);            // = ((x * 1.0) - -(5.0))
  print(exp.simplify()); // = (x + 5.0)

  Expression expDerived = exp.derive('x');

  print(expDerived);            // = (((x * 0.0) + (1.0 * 1.0)) - -(0.0))
  print(expDerived.simplify()); // = 1.0

Alternatives #

Here are some other Dart libraries that implement similar functionality to math_expression: parsing and evaluating mathematical expressions.

  • expressions: an elegant and small library to parse and evaluate simple expressions.
  • function_tree: a library for parsing, evaluating and plotting single- and multi-variables numerical functions.

To the author's knowledge math_expressions is currently the only library supporting interval arithmetics.

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Publisher

leonhardt.co.nz

A library for parsing and evaluating mathematical expressions, supporting real numbers, vectors, and basic interval arithmetic.

Repository (GitHub)
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Documentation

API reference

License

MIT (LICENSE)

Dependencies

vector_math

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